<div ng-controller="mouseenter" class="index_li">
    <ul>
        <li ng-mouseenter="mouse(1)">1</li>
        <li ng-mouseenter="mouse(2)">2</li>
        <li ng-mouseenter="mouse(3)">3</li>
        <li ng-mouseenter="mouse(4)">4</li>
    </ul>
</div>